When you execute the shell script, it will display HTML, if that's what the program outputs.
Shell scripts are usually not very user interactive - I don't think I understand what you're trying to do. If you need HTML rendering, I dont think there's another way except thru a web-server and using a browser. It would be possible to output the HTML and then get the HTML rendered in a web-broswser, but is that really a shell-script?
If you need a lot of interactivety, you need to rewrite everything that has to do with output and input from the users. I suggest looking into ncurses, http://www.php.net/manual/en/ref.ncurses.php